LONDON (CBS News) -- The mother of the two Boston bombing suspects told reporters in southern Russia on Thursday that she regretted ever moving her family to the United States, as her husband said he would travel to the U.S. later in the day to see his surviving son.

"Why did I even go there?" Zubeidat Tsarnaeva said through tears after CBS News correspondent Charlie D'Agata asked her if she regretted the move.

"America took my kids away from me," she declared through tears, saying she wished she had remained in a village in the southern Russian region of Dagestan instead of emigrating to Boston in 2002.

Tsarnaeva was adamant that police arrested her elder son alive and that he died later in custody. Says said she saw video of him on internet, referring to an amateur video which showed a man stripped of most of his clothing being taken into custody on the day of Tamerlan's death and Dzhokhar's eventual arrest.

"What have you done to my son? Why did they have to kill him?" the emotional mother asked during the news conference. She was vague when asked who she believed was behind the conspiracy she claims set her kids up.

"Politics is a dirty game, not everyone can speak about this. I do not know who needed this. I know one thing, this has been done and that it was not my children," she told reporters. "Everything that has been said does not match our children."

She said she called Tamerlan after the Boston bombs went off, and he told her "don't worry." She said he did not mention the FBI being in contact with him following the blasts, as has been reported based on interviews with her husband.

Anzor Tsarnaev, who also spoke at the news conference with this wife, said he would travel back to the U.S. later Thursday. His wife was also planning to travel to the U.S., but it wasn't immediately clear whether she would travel with Anzor on Thursday. Zubeidat Tsarnaeva faced legal trouble in the U.S. previously, being charged with shoplifting.

She said at the news conference that her lawyers in the U.S. had given her assurances that her arrest warrant won't be an issue if she travels back to America. The mother added that she would be "happy" to give up her U.S. citizenship, and that she was "thinking about it."

Both parents of Tamerlan and Dzhokhar Tsarvaev were interviewed at length on Wednesday by Russian and U.S. officials in Makhachkala, Dagestan's capital.

U.S. investigators looking for the motive behind the brothers' alleged double bombing attack on the Boston Marathon have been keen to learn more about what Tamerlan did and whom he met with during a seven-month visit from Boston back to southern Russia just several years ago.

The U.S. team of investigators traveled Tuesday from Moscow to the predominantly Muslim province of Dagestan, which is next to Chechnya, to question the parents, "because the investigation is ongoing, it's not over," an official told The Associated Press on condition of anonymity.

On "CBS This Morning" Wednesday, CBS News senior correspondent John Miller reported that the FBI legal attache assigned to the U.S. Embassy in Moscow had joined with the Russian security services, the FSB, to work on a joint investigation, tracking down people, retracing steps Tamerlan took during his recent trips to parts of Russia where Chechen Islamic militants have long posted a serious security threat.

Miller said that among the most urgent questions for the investigators would be trying to establish whether Tamerlan met a bomb maker or instructor in Russia, or whether he actually got any hands-on experience or testing with explosive devices.

In his questioning in the hospital, Dzhokhar Tsarnaev said he and his brother were self-taught and self-radicalized.

"But you don't take that at face value, so you go back over that trip," said Miller. "Remember the younger brother may not know what his brother did in the Russian trip because he didn't go."

Miller said a Muslim convert known to the Tsarnaev family only as Misha, who family members have claimed steered Tamerlan toward a strict interpretation of Islam, probably wouldn't be the bomb maker or teacher. However, Miller said it's possible he connected Tamerlan with someone linked to extremists back in Russia.

Asked about Misha on Thursday, Tamerlan's mother said he was "very nice, very gentle."

"When he was coming (to) our house there was nothing not to like about him, nothing extreme." Asked whether Misha brought her and her family closer to Islam, she replied that he had. He led her to "pray more," Zubeidat Tsarnaeva said, adding that she had not seen Misha in two or three years.

Russian intelligence officials warned the FBI in 2011 that they had concerns Tamerlan might be connecting with, or trying to connect with, Chechen Islamic radical groups in the Caucuses region. The FBI looked into the young man, but found nothing incriminating enough to put him under increased surveillance.

It emerged Thursday, however, that the CIA had named Tamerlan to a terrorist database later in 2011, according to officials close to the investigation who spoke to The Associated Press on condition of anonymity.

It wasn't immediately clear what led the CIA to put Tamerlan's name on the huge, classified "Terrorist Identities Datamart Environment," or TIDE, which currently lists more than half a million individuals.

His name's mere existence on the list, however, is expected to be a major focus of the looming congressional inquiries on the Obama administration's response to the bombings and efforts to follow up on the tips received from Russia.

Immediately after the Boston bombings, law enforcement and city officials were quick to say there had been no information suggesting a significant terror threat or looming plot against Boston in the days and weeks before the attack.

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